Just my thoughts on the topic. I have a '72 LUV with a 425 hp Vortec and th350 with 2200 stall speed B&M tc. I'm running a Ford 8.8 posi with 3:73s and 26" tall tires. At 70 mph I'm turning 3500 rpm, so I try to keep it down below 60 on the freeway. I'm a drag racer so I chose 3:73s as a middle ground, but kind of now wish I would have gone with 3:55s. These little LUVs are lite (2700 lbs) so one doesn't need a lot of gear to get them off the line. I chose the Ford 8.8 because they're the new 9" and can handle 6 to 700 hp, and come with disc brakes. Yes, you would most likely have to narrow the housing and get custom axles, to do it right, but in the long run it would be worth it. That's my two cents.
3rd Luv
ps: Didn't see my first reply so did it again. Tried to cancel, but oooopps!